Bentonite

Bentonite is an absorbent clay — colloidal hydrated aluminium silicate from weathered volcanic ash — that swells as it absorbs water. Food-industry uses cover winemaking fining, where it removes haze-forming proteins; clarification of fruit juices and vegetable oils; bakery additives that slow staling; and stabilisers and filter aids. Its powerful adsorption also makes it useful in animal feeds as a binder and mycotoxin adsorbent. Food-grade bentonite must meet purity specifications, since natural clays can carry heavy metals; properly sourced, it is a versatile, natural processing aid with centuries of use.